TWI516888B - Servo control device - Google Patents

Description

Servo control unit

The present invention relates to a servo control device that performs drive control of a control object.

A servo control device for an industrial machine such as a robot, a press device, or a line automation device that drives and controls an engine (motor or motor) that drives a mechanical system (position or speed) And control is performed in such a manner that the motion of the motor follows the command. When the rigidity of the mechanical system is low (the mechanical system of the drive is in the shape of an arm, or the case where the load machine is driven by a low-rigidity shaft or a reducer), the movement of the mechanical front end is The motion of the motor will vary due to the deflection of the low rigidity. Further, when the rigidity of the mechanical system is low, vibration is generated after the change of the command such as the stop. For these reasons, the motion of the mechanical front end has an error with respect to the command, which deteriorates the control accuracy.

In the technique described in Patent Document 1, the second-order differential value of the time is obtained for the position command value generated by the position command block, and this is multiplied by the gain ( Gain) Constant to find the correction value. Then, follow the original position with the motor The method of setting the command value plus the correction position command value obtained by the correction value is controlled.

Further, in the technique described in Patent Document 1, it is described that virtual differentiation can be used instead of using pure differential. Further, when the pattern of the command speed is trapezoidal, the timing at which the acceleration of the command is changed is changed, and the correction value is generated using the correction pattern of the time series set in advance.

Further, in the servo control device, there is a case where the industrial machine periodically performs a specific pattern operation in a cycle that is not necessarily fixed. In such a case, a method having, for example, a command function portion called an electronic cam (cam) is employed. In this manner, the phase within the display period is used and the phase signal that increases or decreases over time is used. The command function portion then uses a phase signal based data or data table reference to generate periodic position commands. Thereby, a position command of the same shape is generated for the phase reversal, and the motor position is followed by the position command. The technique described in Patent Document 2 is a technique for further correcting the position command by using the servo control device of the command function unit to improve the control accuracy.

The technique described in Patent Document 2 is intended to improve the control accuracy of the servo control device that periodically performs the operation of the same pattern, and to correct the command. In this technique, a phase signal (phase command value) is taken as an input and a command function portion (position pattern generator) is used to generate a periodic position command (position pattern). Then, in order to correct the delay of the follow-up control unit (position control system), the command function unit is used to make The phase advancement position command, and the correction value is calculated by multiplying the second order differential value or the third order differential value of the position command with respect to time.

Further, in the technique described in Patent Document 2, there is described a technique of switching whether or not the above-described correction value is added in accordance with the magnitude of the absolute value of the second-order differential value or the third-order differential value of the position command, thereby suppressing noise. (noise) overlaps the position command.

[Patent Literature]

(Patent Document 1) Japanese Patent Laid-Open Publication No. 2003-76426

(Patent Document 2) Japanese Patent Laid-Open Publication No. 2011-67016

However, in the prior art of the former, since the signal becomes a noise signal when the second-order differentiation of the position command is performed, there is a problem that it is difficult to perform high-precision control. Further, when virtual differentiation is used instead of pure differentiation as a countermeasure against a noise problem, there is a problem that it is difficult to perform high-precision control due to phase delay. Further, in the method of obtaining the correction value by the predetermined pattern at the time when the acceleration of the extraction command changes, there is a problem that it can only correspond to the specific command shape.

Further, in the latter prior art, since the correction value is calculated by using the second-order differential or the third-order differential of the position command outputted by the command function unit with respect to time, the command noise becomes large and the control with high precision becomes Difficult problem. Moreover, by switching whether or not to perform correction according to the magnitude of the second-order differential or the third-order differential of the position command, corresponding to the noise However, since the result is still affected by noise when the result is corrected, there is a problem that control with high precision becomes difficult.

The present invention has been developed in view of the above circumstances, and an object thereof is to obtain a servo control device that can control a periodic operation with high precision even if the control target is low in rigidity.

In order to solve the above problems and achieve the object, the present invention provides a tracking control unit that controls a motor system that is driven by the motor to correspond to a motor position or a motor speed of the motor. The motor motion follows the motor motion command to control the motor, and the command function unit inputs a phase signal indicating a phase of the cyclic operation performed by the control target, and calculates a first function by a predetermined function. a mechanical motion command corresponding to the phase signal; a second derivative function unit that inputs the phase signal and uses a predetermined second function as a second derivative function, and calculates a second function corresponding to the phase signal The value is a second-order differential basic signal, wherein the second derivative function is a function obtained by second-order differentiation of the first function by the phase signal; and a correction value calculation unit that inputs a phase for indicating a time differential value of the phase signal Speed, and the aforementioned second-order differential base signal, and using the aforementioned squared phase velocity The first command correction value for correcting the motor motion command is calculated by multiplying the value, the second-order differential base signal, and the first constant; and the correction addition unit is based on the first command correction value and the mechanical motion command The added value is used to calculate the motor motion command.

According to the present invention, even if the object to be controlled is low in rigidity, the effect of controlling the periodic operation with high precision can be achieved.

1‧‧‧Control object

2‧‧‧ Follow the Control Department

3A, 3B‧‧‧ Phase Generation Department

5A, 5B‧‧‧ Command Generation Department

11‧‧‧Motor

12‧‧‧Flexible Department

13‧‧‧Mechanical load

51‧‧‧Command Function Department

52‧‧‧Secondary Guide Function

53‧‧‧Correction value calculation unit

53a‧‧‧ Square Computing Department

53b‧‧‧Constant Multiplication Department

53c‧‧‧Second Order Differential Multiplication Department

54A, 54B‧‧‧ Correction Value Addition Department

62‧‧‧One lead function department

63‧‧‧Acceleration time calculation unit

64‧‧‧Attenuation correction value calculation unit

100A, 100B‧‧‧ servo control device

Cg‧‧‧viscosity constant

f(θ)‧‧‧ instruction function

f’(θ)‧‧‧First derivative function

f"(θ)‧‧‧secondary derivative function

G(s)‧‧‧transfer function

JL‧‧‧load inertia

JM‧‧‧Motor Inertia

Kg‧‧·spring constant

s‧‧‧Operator

Xb‧‧‧ second-order differential fundamental signal

Xb1‧‧‧ first-order differential basis signal

Yh‧‧‧ instruction correction value

Yha‧‧‧revised value when accelerating

Yhz‧‧‧ attenuation correction value

yL‧‧‧load position

Ym‧‧‧Motor position

Yr‧‧‧Motor Position Command

Yr0‧‧‧Mechanical position command

Α‧‧‧ phase acceleration

Θ‧‧‧ phase signal

Ω‧‧‧ phase speed

ω _z ‧‧‧anti-resonance frequency

τm‧‧‧Motor torque

ζ‧‧‧Attenuation coefficient

Fig. 1 is a block diagram showing the configuration of a servo control device according to a first embodiment of the present invention.

Fig. 2 is a schematic view showing a configuration example of a control object.

Fig. 3 is a block diagram showing the configuration of a servo control device according to a second embodiment of the present invention.

Hereinafter, a servo control device according to an embodiment of the present invention will be described in detail based on the drawings. Further, the present invention is not limited to the embodiments.

Embodiment 1

Fig. 1 is a block diagram showing the configuration of a servo control device according to a first embodiment of the present invention. The servo control device 100A of the first embodiment is a device that drives a control motor (a motor 11 to be described later) and a control target 1 composed of a mechanical system that is driven by the motor 11.

The control target 1 is, for example, an industrial machine such as an industrial robot, a press device, or a line automation device, and includes a motor 11 and a mechanical system connected to the motor 11. The servo control device 100A drives and controls a control target using an actuator such as a servo motor. The servo control device 100A causes the control target 1 to perform a motor torque τm by causing the motor of the control target 1 to generate a motor torque τm. The desired action. Specifically, the servo control device 100A sequentially changes the motor torque τ m based on the motor position ym detected by the detector (not shown), thereby controlling the operating position of the motor 11 so that the control target 1 performs the desired operation. action.

The servo control device 100A includes a phase generation unit 3A, a command generation unit 5A, and a follow-up control unit 2. The phase generating unit 3A generates a phase signal θ indicating the phase of the periodic operation performed by the control target 1 and a phase velocity ω indicating the rate of change of the phase signal θ, and outputs the phase velocity ω to the command generating unit 5A. The command generation unit 5A calculates the motor position command yr by the calculation described later, and outputs the calculated motor position command yr to the following control unit 2.

The following control unit 2 inputs the motor position command yr output from the command generating unit 5A and the motor position ym detected by the control target 1, and generates the motor torque τ m so that the motor position ym follows the motor position command yr. That is, the following control unit 2 generates and controls the motor torque τ m so that the motor motion indicated by the motor position ym follows the motor position command yr, that is, following the motor motion command.

In the present embodiment, the case where the phase generating unit 3A is inside the servo control device 100A will be described. However, the phase generating unit 3A may not be provided inside the servo control device 100A. The servo control device 100A may be configured to input, for example, a signal such as a rotational position of an external device that performs a rotational operation from the outside so as to synchronize with the operation of the external device.

The phase generating portion 3A is, for example, passed over time The phase signal θ is generated from the externally designated phase velocity ω, and the phase velocity ω and the phase signal θ are output to the command generating unit 5A. Alternatively, the phase generating portion 3A may output the phase signal θ which is increased or decreased with time from the external input to the command generating portion 5A, and output the phase velocity ω corresponding to the time differential of the phase signal θ to the command. The generating portion 5A. In this case, the phase generating unit 3A calculates the phase velocity ω using a filter having a sufficiently large noise removing effect to prevent the noise component due to the quantization included in the phase signal θ from being caused by the differential. The operation becomes larger. In this way, the phase generating unit 3A outputs the phase signal θ and the phase velocity ω generated without including the noise component to the command generating unit 5A.

Next, the configuration and operation of the command generating unit 5A will be described. The command generation unit 5A inputs the phase signal θ and the phase velocity ω output from the phase generation unit 3A, calculates the motor position command yr, and outputs it to the following control unit 2. The command generation unit 5A includes a command function unit 51, a second derivative function unit 52, a correction value calculation unit 53, and a correction value addition unit 54A.

In the command generation unit 5A, the phase signal θ outputted from the phase generation unit 3A is input to the command function unit 51 and the second derivative function unit 52, and the phase velocity ω output from the phase generation unit 3A is input to the correction value calculation. Part 53.

The command function unit 51 calculates the mechanical position command yr0 with respect to the control target 1 based on the phase signal θ. At this time, the command function unit 51 calculates the mechanical position command yr0 using the command function f(θ) set in advance. In other words, the command function unit 51 is configured by a preset command. The function f(θ) (first function) calculates a mechanical motion command corresponding to the phase signal θ. The instruction function f(θ) is, for example, a number or a data table.

In the case where the command function f(θ) is the data table, the correspondence relationship between the point (value) of the phase signal θ and the point (value) of the mechanical position command yr0 is set in advance in the data table. In the data sheet, the aforementioned correspondence of the predetermined number is set in advance. The command function unit 51 calculates the mechanical position command yr0 by interpolating the reference value of the data table with respect to the input phase signal θ of an arbitrary value. At this time, the command function unit 51 can easily calculate the mechanical position command yr0 by using the linear interpolation method. Further, the command function unit 51 can also use a complicated spline interpolation method or the like. The command function unit 51 outputs the calculated mechanical position command yr0 to the correction value addition unit 54A.

In the secondary derivative function unit 52, a function (second function) corresponding to the second derivative function f"(θ) of the command function f(θ) is set in advance. Here, the second derivative function f" (θ) ) refers to the second-order differentiation of the command function f(θ) by the phase signal θ. The secondary derivative function unit 52 calculates a value of a function corresponding to the input phase signal θ as a second-order differential base signal xb, and outputs it to the correction value calculation unit 53. Here, the second function of the second derivative function unit 52 is, for example, a numerical formula or a data table, similarly to the command function f(θ). Further, the second function is similar to the second derivative function f"(θ) of the command function f(θ) depending on the situation. However, in the case where it is not necessary to describe it rigorously, the second function is written indiscriminately. The function and the second derivative function f"(θ).

In the case where the second function in the second derivative function unit 52 is a data table, the point (value) of the phase signal θ is equivalent to the second derivative function f" The correspondence relationship between the points (values) of (θ), that is, the correspondence between the point (value) of the phase signal θ and the point (value) of the second-order differential base signal xb is set in advance in the data table. The second derivative function unit 52 calculates the second-order differential basic signal xb by interpolating the reference value of the data table with respect to the input phase signal θ of an arbitrary value. The secondary derivative function unit 52 outputs the calculated second-order differential base signal xb to the correction value calculation unit 53.

The correction value calculation unit 53 inputs the second-order differential base signal xb and the phase velocity ω, and calculates a product for correcting the mechanical position using the product of the square of the phase velocity ω, a predetermined constant (the first constant), and the second-order differential base signal xb. The yr0 command correction value yh. The correction value calculation unit 53 outputs the calculated command correction value yh to the correction value addition unit 54A. Here, the predetermined constant is set in accordance with the mechanical constant related to the rigidity or vibration of the control target 1, and is set to the reciprocal of the square of the anti-resonance frequency of the control target 1 to be described later.

The correction value calculation unit 53 includes a square operation unit 53a, a constant multiplication unit 53b, and a second-order differential multiplication unit 53c. In the correction value calculation unit 53, the square operation unit 53a calculates the square of the phase velocity ω and outputs it to the constant multiplication unit 53b. Then, the constant multiplication unit 53b multiplies the output from the square operation unit 53a by a predetermined constant (for example, a value based on the inverse of the square of the anti-resonance frequency ω _z of the control target 1). The constant multiplication unit 53b outputs the multiplied value to the second-order differential multiplication unit 53c. Further, the second-order differential multiplication unit 53c performs multiplication of the output from the constant multiplication unit 53b and the second-order differential base signal xb, and calculates a command correction value yh. Then, the second-order differential multiplication unit 53c outputs the command correction value yh to the correction value addition unit 54A.

Here, the order of multiplication of each unit in the correction value calculation unit 53 is not particularly limited to the above-described order. The correction value calculation unit 53 calculates that the command correction value yh is obtained by multiplying the inverse of the value obtained by dividing the square of the phase velocity ω and the square of the inverse resonance frequency ω _z by the second-order differential base signal xb. can.

The correction value addition unit 54A outputs the result (added value) obtained by adding the command position correction value yh outputted by the correction value calculation unit 53 to the mechanical position command yr0 output from the command function unit 51, and outputs it as the motor position command yr. Follow the control unit 2. In this manner, the command generation unit 5A calculates the motor position command yr based on the phase signal θ and the phase velocity ω and outputs the result to the follow-up control unit 2 by the above operation.

The following control unit 2 inputs the motor position command yr output from the command generating unit 5A and the motor position ym detected from the control target 1. The tracking control unit 2 generates the motor torque τm while controlling the current of the motor 11 in the control target 1 so that the motor position y follows the motor position command yr. The tracking control unit 2 uses, for example, cascade control including motor position control, motor speed control, and motor current control.

Next, in order to explain the effects obtained by the present embodiment, first, the characteristics of the control target 1 considered in the present embodiment will be described. Fig. 2 is a schematic view showing a configuration example of a control object.

The control object 1 is coupled to the motor 11 and the mechanical load 13 by an elastic portion 12 such as a shaft. Then, in the control object 1, by the servo The motor torque τ m generated by the service control device 100A drives the motor 11 and transmits the mechanical load 13 through the elastic portion 12.

The load inertia (inertia) of the mechanical load 13 is JL, the load position at the position of the mechanical load 13 as the operation is yL, the spring constant of the elastic portion 12 is Kg, the viscosity constant of the elastic portion 12 is Cg, and the motor inertia of the motor 11 For JM.

The relationship between the load position yL and the motor position ym in the case where the control target 1 is driven by the motor torque τ m is expressed by the following equation (1). In addition, in the following description, the s of the symbol is a Laplace operator, and is equivalent to the operator of time differentiation.

yL/ym=1/(s ² /ω _z ² +2ζ.s/ω _z +1). . . (1)

The ω _z of the equation (1) is the anti-resonance frequency of the control object 1, and ζ is the attenuation coefficient, which is expressed by the following equations (2) and (3), respectively.

ω _z =(Kg/JL) ^(1/2) . . . (2)

ζ=Cg/{2(JL.Kg) ^(1/2) }. . . (3)

Here, the transfer function from the motor position command yr to the motor position ym as a result of the control by the action of the control unit 2 is expressed as G(s). In other words, when the following equation (4) is satisfied, the transfer function from the motor position command yr to the load position yL is expressed by the following equation (5).

Ym/yr=G(s). . . (4)

yL/yr=G(s){1/(s ² /ω _z ² +2ζ.s/ω _z +1)}. . . (5)

In the case where the rigidity of the mechanical system in the control object 1 is low, usually since the attenuation coefficient ζ becomes significantly smaller than 1, it is When the attenuation coefficient ζ is considered to be sufficiently small and ignored, the equation (5) can be approximated by the following equation (6).

yL/yr=G(s){1/(s ² /ω _z ² +1)}‧‧‧(6)

Therefore, even if the response of the following control unit 2 is set to high speed and high precision (even if the transfer function G(s) is close to 1), the equation (6) includes the secondary resonance characteristic. Therefore, it can be understood that the response of the load position yL has an error, and the vibration is performed at the anti-resonance frequency ω _z with respect to the change of the motor position command yr. Thus, the anti-resonance frequency ω _z corresponds to the vibration frequency of the mechanical system.

Next, the detailed characteristics of the command generating unit 5A will be described. The command generation unit 5A calculates the command correction value yh represented by the following equation (7) by inputting the phase signal θ by performing the above-described operation.

Yh=f”(θ)‧ω ² /ω _z ² ‧‧‧(7)

Here, the time differentiation of the mechanical position command yr0 (i.e., f(θ)) is considered. The first-order differential value and the second-order differential value of the mechanical position command yr0 are expressed by the following equations (8) and (9).

Df(θ)/dt={df(θ)/dθ}(dθ/dt)‧‧‧(8)

d ² f(θ)/dt ² ={d ² f(θ)/dθ ² }(dθ/dt) ² +{df(θ)/dθ}(d ² θ/dt ² )‧‧‧(9)

Here, when the phase velocity ω which is the time differential of the phase signal θ is fixed or changed very small in the period under consideration, the equation (9) becomes the following equation (10).

d ² f(θ)/dt ² ={d ² f(θ)/dθ ² }(dθ/dt) ² ‧‧‧(10)

In the equation (10), when d ² f(θ)/dθ ^{2 is} rewritten as f"(θ), dθ/dt is rewritten as ω, f(θ) is rewritten as yr0, and time differential is rewritten as an operator. In the case of s, the equation (10) can be rewritten as the following equation (11). Then, the equation (7) indicating the command correction value yh is expressed by the following equation (12).

s ² yrO=f”(θ)ω ² ‧‧‧(11)

Yh=(s ² /ω _z ² )yrO‧‧‧(12)

Thus, it is irrelevant that the mechanical position command yr0 is not time-differentiated on the installation, but can be equivalently multiplied by a predetermined constant for the time-dependent second-order differential value of the mechanical position command yr0. The operation instruction correction value yh.

Further, since the motor position command yr is the sum of yr0 and yh, the transfer function from the mechanical position command yr0 to the motor position command yr is expressed by the following equation (13). As a result, the transfer function from the mechanical position command yr0 to the load position yL is expressed by the following equation (6) by combining the equations (6) and (13).

Yr/yrO=(s ² /ω _z ² +1)‧‧‧(13)

yL/yrO=G(s)‧‧‧(14)

Therefore, by making the response of the following control unit 2 high-speed and high-precision, and making the transfer function G(s) close to 1, even if the rigidity of the control target 1 is low, the machine can be followed by the high-speed and high-precision with the load position yL. The position command yr0 is controlled.

The command generation unit 5A sets the predetermined setting in the constant multiplication unit 53b by using the anti-resonance frequency ω _z which is a mechanical characteristic of the control target 1 (for example, a mechanical characteristic related to the rigidity or the vibration frequency). The constant income. For example, the characteristics of the command generating unit 5A are externally set in accordance with the mechanical characteristics of the control target 1, whereby high-precision control of the control target 1 can be realized.

Further, the anti-resonance frequency ω _z corresponds to the vibration frequency of the control target 1. Therefore, the servo control device 100A can be configured, for example, by automatically measuring the vibration frequency in the servo control device 100A and setting the anti-resonance frequency ω _z to the command generation unit 5A.

The effect that can be obtained by the high-speed high-precision control described above can be obtained by simply setting the transfer function from the mechanical position command yr0 to the motor position command yr to the equation (13). This property is basically the same as the method described in Patent Document 1.

On the other hand, in one of the features of the servo control device 100A of the present embodiment, the second-order differential basic signal xb is calculated using the secondary derivative function unit 52 which is set as a function of the phase signal θ, and the arithmetic command correction value yh is calculated as The square of the phase velocity ω is the product of the second-order differential base signal xb and a predetermined constant. As described above, in the servo control device 100A, the command correction value yh represented by the equation (12) is not directly calculated by performing the second-order time differentiation.

As a comparison between the prior art and the servo control device 100A, it is assumed that the case where the second-order time differential as shown in the equation (12) is actually calculated in real time is considered. In the calculation of the actual servo control device 100A, a numerical operation in which the effective number of bits is a finite length is used. In this case, when the calculation of the phase signal θ in the phase generating portion 3A is performed, Mix the quantization noise into the ideal value. Further, in the command function unit 51, in the four arithmetic operations of the process of outputting the mechanical position command yr0 from the phase signal θ (the process of performing the interpolation operation based on the data table reference), the quantization due to the estimation error or the truncation error is mixed. Noise.

When the second-order differential operation of the time-differentiation is performed on the mechanical position command yr0 in which such quantization noise is mixed, the component of the quantization noise becomes very large and becomes impossible to be directly used for the command correction value. The operation of yh. Further, in order to suppress quantization noise, when the filter is caused to function in the actual time calculation, it is difficult to achieve high-precision control because a delay depending on the filter occurs.

On the other hand, in the present embodiment, since the calculation of the command correction value yh is performed based on the reference value set with the function of the phase signal θ or the second derivative function unit 52 of the data table, it is possible to suppress the cause of the numerical value. The quantization and the increase of the time-differentiated noise component. As a result, high-precision control can be easily realized without adding a filter or the like.

In this manner, the servo control device 100A calculates the second-order differential base signal xb corresponding to the second-order differential value related to the phase signal θ of the mechanical position command yr0 by the second derivative function unit 52. Then, the servo control device 100A calculates the command correction value yh by multiplying the second-order differential base signal xb by the phase generation unit 3A by the square of the phase velocity ω generated without including the noise component, and a predetermined constant. Thereby, it is also possible to change the phase velocity ω (change the cycle of the cycle operation performed by the control target 1), and to realize the control characteristic equivalent to the second-order time differential using the mechanical position command yr0. Also, since the time is not performed in the actual calculation The motor position command yr that suppresses the noise component of the signal can be calculated.

Further, in the calculation of the phase velocity ω in the phase generating portion 3A, even if a slow-passing low-pass filter for removing noise is used, as long as the phase velocity ω changes slowly, it is low. The effect of the operation of the filter correction value yh caused by the delay of the pass filter is also small. Therefore, the servo control device 100A does not deteriorate the control accuracy and can remove the adverse effects of noise.

In the present embodiment, the command function f(θ) of the command function unit 51 and the second derivative function f"(θ) of the second derivative function unit 52 are calculated by a predetermined data table and interpolation calculation. The case of the data sheet is not particularly limited. The command function f(θ) and the second derivative function f"(θ) can be calculated as a formula relative to the phase signal θ. In the case, even a very complicated operation can be tabled in advance to avoid the problem of calculating time in the actual time action. In addition, when the data table corresponding to the second derivative function f"(θ) is prepared in advance, the data table is calculated in advance using a high-precision floating-point arithmetic operation or the like, and the data table can be created without mixing noise errors. High-frequency noise problems are not generated and high-precision control is achieved.

Further, as the function f(θ) previously set in the command function unit 51, it is not necessary to set a numerical value table with respect to a point of the finite number of phase signals θ based on the mathematical expression. In this case, it is possible to easily set a periodic motion of an arbitrary pattern which is difficult to represent in terms of a number. In such a case, as a simple manner of the data table based on the instruction function f(θ) of the instruction function portion 51, it is assumed that the second is related to the point of the adjacent phase signal θ by double. When the data table corresponding to the second derivative function f"(θ) is obtained by the difference calculation, the high-frequency component in the region of the phase signal θ may be excessively large.

When the high-frequency component is too large, the smoothing operation by the filter is required, but the smoothing operation may be performed in an off-line state instead of the actual time calculation. Therefore, the high frequency component can be suppressed without causing a phase error.

Specifically, a technique called a zero phase filter is used in the filter operation that functions in the region of the phase signal θ. That is, the filter operation for suppressing the characteristics of the high-frequency component of the phase signal θ is applied to both the positive direction and the reverse direction of the phase signal θ. Thereby, the high-frequency component can be suppressed without causing a phase error, and a function corresponding to the second derivative function f"(θ) in the second derivative function portion 52 can be created. As a result, the second derivative function is used. When the part 52 performs the calculation of the actual time operation of the data table reference and the interpolation operation, the high frequency noise of the output signal is not increased, and the anti-resonance which has a large influence on the vibration or the control error of the control object 1 can be performed. The frequency characteristic near the frequency ω _{z is} subjected to high-accuracy actual time calculation, and thus high-precision control can be realized.

Further, in the present embodiment, a function corresponding to the function f(θ) of the command function unit 51 and f"(θ) of the second derivative function unit 52 is set as the phase signal θ with respect to the predetermined number. The case of the data sheet of the point is explained, but the mathematical expression may be set in advance as the command function f(θ) or the second derivative function f"(θ). For example, in the case where the command function f(θ) or the second derivative function f"(θ) can be realized by a function capable of performing actual time calculation, it is also possible to perform relative information without setting a data table. The numerical calculation of the phase signal θ.

As described above, in the present embodiment, the case where the servo control device 100A performs position control will be described. Specifically, the command function unit 51 that inputs the phase signal θ calculates the mechanical position command yr0, and the correction value calculation unit 53 that inputs the phase signal θ and the phase velocity ω calculates the command correction value yh, and the correction value addition unit 54A The motor position command yr is calculated. Then, the following control unit 2 controls the control target 1 such that the motor position ym follows the motor position command yr.

Further, the servo control device 100A can also operate in the same order as the speed of the speed. In this case as well, the same effect as in the case of the position control can be obtained. In this case, the command function unit 51 that inputs the phase signal θ calculates the mechanical speed command as the mechanical motion command, and the correction value calculation unit 53 that inputs the phase signal θ and the phase velocity ω calculates the command correction value of the speed. The correction value addition unit 54A calculates a motor speed command as a motor motion command. Then, the following control unit 2 controls the control target 1 such that the motor speed as the motor motion follows the motor speed command.

As described above, according to the first embodiment, it is possible to suppress the vibration or the control error caused by the low rigidity of the control target 1 that performs the periodic operation, and also to generate the noise due to the signal quantization of the command while changing the cycle. Problems and achieve high precision control. Therefore, even if the control target 1 is low in rigidity, the periodic operation can be controlled with high precision.

Embodiment 2

Next, a second embodiment of the present invention will be described using FIG. Fig. 3 is a block diagram showing the configuration of a servo control device according to a second embodiment of the present invention. Among the components of the third embodiment, the same components as those of the servo control device 100A of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.

The servo control device 100B of the second embodiment performs more complicated setting or calculation than the servo control device 100A, thereby achieving more precise control than the servo control device 100A. The servo control device 100B of the present embodiment includes the primary guidance function unit 62 and the acceleration correction value calculation unit 63, whereby the control accuracy can be improved even when the phase velocity ω indicating the rate of change of the phase signal θ is not constant. . Further, the first derivative function unit 62 and the attenuation correction value calculation unit 64 are provided, whereby the control accuracy can be improved even when the attenuation in the vibration characteristics of the control target 1 is large.

The servo control device 100B includes a phase generation unit 3B, a command generation unit 5B, and a follow-up control unit 2. Similarly to the phase generating unit 3A of the first embodiment, the phase generating unit 3B outputs the phase signal θ and the phase velocity ω to the command generating unit 5B. Further, the phase generating unit 3B outputs a phase acceleration α corresponding to the time differential of the phase velocity ω to the command generating unit 5B. The phase acceleration α can be output as a component that does not include noise by setting a time series pattern or the like in advance.

The command generation unit 5B inputs the phase signal θ, the phase velocity ω, and the phase acceleration α to calculate the motor position command yr, and outputs the calculated motor position command yr to the following control unit 2. Command generation unit 5B The command function unit 51, the second derivative function unit 52, the correction value calculation unit 53, the correction value addition unit 54B, the primary guidance function unit 62, the acceleration correction value calculation unit 63, and the attenuation correction value calculation unit 64 are included.

In the command generation unit 5B, the phase signal θ output from the phase generation unit 3B is input to the instruction function unit 51, the second derivative function unit 52, and the primary guidance function unit 62. Moreover, the phase velocity ω output from the phase generation unit 3B is input to the correction value calculation unit 53 and the attenuation correction value calculation unit 64. Further, the acceleration time correction value calculation unit 63 inputs the phase acceleration α output from the phase generation unit 3B.

In the primary function unit 62, a third function corresponding to the primary derivative function f'(θ) of the command function f(θ) in the command function unit 51 is set in advance. The third function corresponding to the first derivative function f'(θ) is a function equivalent to the first-order differentiation of the command function f(θ) by the phase signal θ. The primary function unit 62 uses the value of the third function corresponding to the input phase signal θ as the first-order differential basic signal xb1, and outputs it to the acceleration-time correction value calculation unit 63 and the attenuation correction value calculation unit 64. The third function corresponding to the primary derivative function f'(θ) is, for example, a mathematical expression or a data table, similarly to the command function f(θ) or the second derivative function f"(θ).

In the case where the third function corresponding to the first derivative function f'(θ) is the data table, the correspondence between the point (value) of the phase signal θ and the point (value) of the first-order differential base signal xb1 is The predetermined number is preset in the data sheet. The primary derivative function unit 62 calculates the first-order differential basic signal xb1 by interpolating the reference value of the data table with respect to the input phase signal θ of an arbitrary value. The first derivative function unit 62 converts the calculated first-order differential basic signal xb1 The acceleration correction value calculation unit 63 and the attenuation correction value calculation unit 64 are outputted.

The acceleration time correction value calculation unit 63 inputs the first-order differential base signal xb1 and the phase acceleration α, and calculates a product of the first-order differential base signal xb1 and the phase acceleration α and a predetermined constant (second constant) as the acceleration correction value yha. . The acceleration time correction value calculation unit 63 outputs the calculated acceleration time correction value yha to the correction value addition unit 54B.

The predetermined constant used by the correction value calculation unit 63 in the acceleration is set in accordance with the mechanical constant related to the rigidity or vibration of the control target 1 in the same manner as the predetermined constant used in the correction value calculation unit 53 of the first embodiment. For example, the predetermined constant used by the correction value calculation unit 63 at the time of acceleration is set so as to be the inverse of the square of the anti-resonance frequency ω _z of the control target 1. Therefore, the acceleration correction value yha can be calculated using the following equation (15).

Yha=f'(θ)‧α/ω _z ‧‧‧(15)

Here, the time-dependent second-order differential value of the mechanical position command yr0 (i.e., f(θ)) can be expressed by the formula (9) as described in the first embodiment. When the condition that the change in the phase velocity ω assumed in the first embodiment is sufficiently small is not satisfied, the equation (9) can be rewritten as the following equation (16). Further, according to the equations (7) and (15), the sum of the command correction value yh and the acceleration correction value yha can be expressed by the following equation (17).

s ² yrO=f”(θ)ω ² +f'(θ)α‧‧‧(16)

Yh+yha=(s ² /ω _z ² )yrO‧‧‧(17)

The attenuation correction value calculation unit 64 inputs the first-order differential base signal xb1 and the phase velocity ω, and calculates a first-order differential base signal. The product of xb1 and the phase velocity ω and a predetermined constant (the third constant) is used as the attenuation correction value yhz. The attenuation correction value calculation unit 64 outputs the calculated attenuation correction value yhz to the correction value addition unit 54B.

The predetermined constant in the attenuation correction value calculation unit 64 is, for example, a value obtained by multiplying the inverse of the attenuation coefficient ζ of the control target 1 by the inverse of the anti-resonance frequency ω _z . Further, in the equation (8) according to the first embodiment, the following equation (18) is established. Therefore, the calculated attenuation correction value yhz can be expressed by the following equation (19).

s‧yrO=f’(θ)ω‧‧‧(18)

Yhz=(2ζ‧s/ω _z )yrO‧‧‧(19)

The correction value adding unit 54B adds the command correction value yh outputted by the correction value calculation unit 53 and the acceleration time correction value yh outputted by the acceleration time correction value calculation unit 63 to the mechanical position command yr0 output from the command function unit 51. The result obtained by the attenuation correction value yhz is output to the tracking control unit 2 as the motor position command yr. When the transfer function from the mechanical position command yr0 to the motor position command yr is calculated according to the equations (17) and (19), the following equation (20) is obtained.

Yr/yrO=(s ² /ω _z ² +2ζs/ω _z +1)‧‧‧(20)

Therefore, even when the phase acceleration α indicating the change in the phase velocity ω cannot be ignored or the attenuation coefficient 控制 of the control target 1 cannot be ignored, the equations (6) and (20) can be combined. Similarly to the first embodiment, the transfer function from the mechanical position command yr0 to the load position yL is expressed by the equation (14).

As a result, the response of the follow-up control unit 2 is made high. When the speed is high-precision and the transfer function G(s) is close to 1, the control target 1 can be controlled such that the mechanical position command yr0 follows the load position yL with high speed and high precision.

In addition, in the present embodiment, the motor position command yr is added to the mechanical position command yr0, and the motor position command yr is calculated by adding all of the command correction value yz, the acceleration correction value yha, and the attenuation correction value yhz. The method of calculating the motor position command yr is not limited to this method. The command generation unit 5B may calculate the motor position command yr by adding at least one of the acceleration time correction value yha and the attenuation correction value yhz by adding the mechanical position command yr0 and the command correction value yh.

For example, when the motor position command yr is calculated, the acceleration time correction value yha is not added, and the acceleration time correction value calculation unit 63 is not required. Further, when the motor position command yr is not calculated, the attenuation correction value yhz is not added, and the attenuation correction value calculation unit 64 is not required.

As described above, according to the second embodiment, even when the phase velocity ω cannot be ignored or the attenuation coefficient 振动 of the vibration characteristic of the control target 1 cannot be ignored, the control target 1 for performing the periodic operation can be suppressed. The vibration or control error caused by low rigidity, while also changing the cycle period, does not cause the problem of noise due to signal quantization of the command and achieves high-precision control.

(industrial availability)

As described above, the servo control device of the present invention is adapted to drive the control of the control object of the mechanical system with a motor.

1‧‧‧Control object

2‧‧‧ Follow the Control Department

3A‧‧‧ Phase Generation Department

5A‧‧‧Command Generation Department

51‧‧‧Command Function Department

52‧‧‧Secondary Guide Function

53‧‧‧Correction value calculation unit

53a‧‧‧ Square Computing Department

53b‧‧‧Constant Multiplication Department

53c‧‧‧Second Order Differential Multiplication Department

54A‧‧‧Correction Value Addition Department

100A‧‧‧Servo Control Unit

f(θ)‧‧‧ instruction function

f"(θ)‧‧‧secondary derivative function

Xb‧‧‧ second-order differential fundamental signal

Yh‧‧‧ instruction correction value

Ym‧‧‧Motor position

Yr‧‧‧Motor Position Command

Yr0‧‧‧Mechanical position command

Θ‧‧‧ phase signal

Ω‧‧‧ phase speed

τm‧‧‧Motor torque

Claims (8)

A servo control device comprising: a follow-up control unit that controls a motor motion corresponding to a motor position or a motor speed of the motor to control a motor target and a motor system that is driven by the motor; The command function unit inputs a phase signal indicating a phase of the cyclic operation performed by the control target, and calculates a mechanical signal corresponding to the phase signal by a first function set in advance. a second instruction function unit that inputs the phase signal and calculates a value corresponding to the second function of the phase signal as a second-order differential base signal using a second function that is set in advance as a second derivative function, wherein The second derivative function is a function obtained by second-order differentiation of the first function by the phase signal; the correction value calculation unit inputs a phase velocity indicating a time differential value of the phase signal, and the second-order differential basic signal, And using the aforementioned squared phase velocity value, the aforementioned second-order differential basic signal Calculating a first command correction value for correcting the motor motion command by multiplying the first constant; and correcting the addition unit to calculate the motor based on the added value of the first command correction value and the mechanical motion command Motion instruction. The servo control device according to the first aspect of the invention is configured to externally set the first constant in accordance with the mechanical characteristics of the control target. The servo control device according to claim 1, wherein the first constant is a value obtained by reciprocal of a value obtained by squaring an anti-resonance frequency corresponding to a vibration frequency of the control target. The servo control device according to claim 1, wherein the second function is a first data table that displays a correspondence relationship between the phase signal and the second-order differential base signal, and the second derivative function unit uses the foregoing 1 The data table is calculated as the second-order differential basic signal. The servo control device according to any one of claims 1 to 3, further comprising: a first derivative function unit that inputs the phase signal and uses a predetermined third function as a first derivative function to calculate a corresponding The value of the third function of the phase signal is a first-order differential basic signal, wherein the primary derivative function is a function obtained by differentiating the first function by the phase signal; and an acceleration time correction value calculation unit is used for inputting Calculating a phase acceleration for a time differential value of the phase signal and the first-order differential base signal, and calculating a motor motion command by using a product of the first-order differential base signal, the phase acceleration, and a second constant The second command correction value is calculated by the correction addition unit based on the added value of the first and second command correction values and the mechanical motion command. The servo control device according to claim 5, wherein The second constant is a value obtained by reciprocal of a value obtained by squaring the anti-resonance frequency corresponding to the vibration frequency of the control target. The servo control device according to any one of claims 1 to 3, further comprising: a first derivative function unit that inputs the phase signal and uses a predetermined third function as a first derivative function to calculate a corresponding a value of the third function of the phase signal as a first-order differential base signal, wherein the first derivative function is a function obtained by differentiating the first function by the phase signal; and an attenuation correction value calculation unit is configured to input the first one And a third command correction value for correcting the motor motion command by using a product of the first-order differential base signal, the phase velocity, and a third constant, wherein the correction addition unit is used The motor motion command is calculated based on the added value of the first and third command correction values and the mechanical motion command. The servo control device according to claim 7, wherein the third constant is a value obtained by multiplying a product of an attenuation coefficient of the control target and a reciprocal of an anti-resonance frequency corresponding to a vibration frequency of the control target.